Pipeline construction is divided into three phases, each
with its own activities: pre-construction, construction and post-construction.
Pre-Construction
Surveying and staking
Once the pipeline route is finalized crews survey and stake
the right-of-way and temporary workspace. Not only will the right-of-way
contain the pipeline, it is also where all construction activities occur.
Preparing the right-of-way
The clearly marked right of way is cleared of trees and
brush and the top soil is removed and stockpiled for future reclamation. The
right-of-way is then leveled and graded to provide access for construction
equipment.
Digging the trench
Once the right-of-way is prepare, a trench is dug and the
centre line of the trench is surveyed and re-staked. The equipment used to dig
the trench varies depending on the type of soil.
Stringing the pipe
Individual lengths of pipe are brought in from stock pile
sites and laid out end-to-end along the right-of-way.
Construction
Bending and joining the pipe
Individual joints of pipe are bent to fit the terrain
using a hydraulic bending machine. Welders join the pipes together using
either manual or automated welding technologies. Welding shacks are placed over
the joint to prevent the wind from affecting the weld. The welds are then
inspected and certified by X-ray or ultrasonic methods.
Coating the pipeline
Coating both inside and outside the pipeline are necessary
to prevent it from corroding either from ground water or the product carried in
the pipeline. The composition of the internal coating varies with the nature of
the product to be transported. The pipes arrive at the construction site
pre-coated, however the welded joints must be coated at the site.
Positioning the pipeline
The welded pipeline is lowered into the trench using
bulldozers with special cranes called sidebooms.
Installing valves and fittings
Valves and other fittings are installed after the pipeline
is in the trench. The valves are used once the line is operational to shut off
or isolate part of the pipeline.
Backfilling the trench
Once the pipeline is in place in the trench the topsoil is
replaced in the sequence in which it was removed and the land is re-contoured
and re-seeded for restoration.
Post Construction
Pressure Testing
The pipeline is pressure tested for a minimum of eight hours
using nitrogen, air, water or a mixture of water and methanol.
Final clean-up
The final step is to reclaim the pipeline right-of-way and remove
any temporary facilities.
Source:
Dega Damara Aditramulyadi
Student ID : 15512046
Course : KL4220 Subsea Pipeline
Lecturer : Prof. Ir. Ricky Lukman Tawekal, MSE, Ph. D.
Eko Charnius Ilman, ST, MT
Ocean Engineering Program, Institut Teknologi Bandung
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